:I notice a Sparc when I attach the ground clip to the antenna ground on the RCA Radio 88K I have. So I measured it and I have -25 VDC between ground and chassis? Is this normal or a leaking cap?
The only thing I can think of that would introduce a rather strong DC is if there was a leak from the transformer primary to the center tap of the high voltage secondary. The chassis is connected after the output tube cathode bias resistor, which would add DC potential (probably around 25 volts) to the leaking AC. This, however, would be positive, since the cathode of the output tube is positive in relation to the high voltage center tap. If the leak was more towards one of the ends of the high voltage winding, this would make the chassis negative with respect to ground (I think). Connect your positive lead to the chassis and your negative lead to ground if you did not already do so. If the DC voltage is then positive, a leak to the high voltage center tap may be your problem. It is good to note that if the leak occurs at one end of the primary, AC will be introduced with the plug connected one way and no AC will be introduced with it connected the other way.
It is possible to get a DC reading on the DC setting of your meter even with an AC voltage also present (both AC and DC present), but usually the needle vibrates even with this reading.
Try reversing the line cord to see what happens. It may not have much of an effect, since this would only alter AC voltage. Try taking a reading on the AC scale of your meter while reversing the line cord. Most meters when set to the AC scale will also read DC voltages (not accurately), but even with both an AC and DC voltage acting upon the meter, any change in AC voltage due to the plug being reversed should show up. This change would indicate a very probable leak from the primary to the high voltage secondary. If the leak occurs in the dead center of the primary coil, though, you will not notice an AC voltage change when you reverse the line cord (as I said before, if it occurs at one end of the primary, there will be a definite presence and absence of AC when the plug is reversed).
Once you have made all of these tests, I guess it would also be a great idea to disconnect all of the transformer wires and then check for actual leakage from coil to coil using the resistance setting of your meter. If one leak is found, but not others, you may or may not want to replace the transformer. A leak from the primary to the high voltage secondary really will have no affect on the radio's performance as long as it is not grounded, since the line voltage has nothing to do with the set's performance anyway (it may introduce a hum in the audio). With a leak present, however, it is possible that the transformer is breaking down and may develop other leaks in the future. Also, a leak will introduce 110 volts AC to the chassis, depending on how the radio is plugged in, which can be a danger (no more so than AC/DC sets that have the chassis connected directly to the line). If you leave the faulty transformer in place, you may still make a ground connection through a .05 MFD condenser (400 to 600 volt rating preferred).
It could be something else, too. Things like this are confusing because they are not normal and are caused by some abstract problem.
Thomas
Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
Good luck,
Thomas
:A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
:
:Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
:
:A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
:
:Good luck,
:
:Thomas
:I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
:
:
::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
::
::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
::
::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
::
::Good luck,
::
::Thomas
What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
Norm
:Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
:-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
:
:
:
:
::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
::
::
:::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
:::
:::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
:::
:::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
:::
:::Good luck,
:::
:::Thomas
:Hi
:
:What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
:
:Norm
:
:
::Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
::-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
::
::
::
::
:::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
:::
:::
::::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
::::
::::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
::::
::::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
::::
::::Good luck,
::::
::::Thomas
Those meters can be so sensitive just holding a lead gives a reading. Try taking a reading with a resistor across the leads.
Norm
:
:I'm using a Wavtek 37XR Digital Voltmeter. I am measuring from Water Pipe Ground (Neg Lead) to the chassis (Positive Lead) in series.
:
:
:
:
:
:
:
:
::Hi
::
::What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
::
::Norm
::
::
:::Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
:::-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
:::
:::
:::
:::
::::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
::::
::::
:::::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
:::::
:::::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
:::::
:::::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
:::::
:::::Good luck,
:::::
:::::Thomas
:Hi
:
: Those meters can be so sensitive just holding a lead gives a reading. Try taking a reading with a resistor across the leads.
:
:Norm
:
::
::I'm using a Wavtek 37XR Digital Voltmeter. I am measuring from Water Pipe Ground (Neg Lead) to the chassis (Positive Lead) in series.
::
::
::
::
::
::
::
::
:::Hi
:::
:::What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
:::
:::Norm
:::
:::
::::Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
::::-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
::::
::::
::::
::::
:::::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
:::::
:::::
::::::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
::::::
::::::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
::::::
::::::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
::::::
::::::Good luck,
::::::
::::::Thomas
There will always be some leakage especially on humid days. Transformers are wound with wire separated by paper.
Not a problem unless you get a spark and can draw current. Modern meters read voltage only drawing a micro amp or so..
Norm
:Thanx Norm but they both (consoles) read 0 volts AC and 0 Volts DC when AC cord is plugged in one way. The only time I get these readings of AC and DC between ground and the chassis is when I reverse the AC plug and plug it in the other polarity/way. I think the Meter is fine. It's reading what is there and then what isn't there. So this leads back to the original question and that is, why do I read 120 AC and 60VAC between house ground (Water pipe) and the chassis on 2 different consoles when I flip the polarity of the AC cord? and 0 VAC or DC when I flip it back the other way.
:
:
:
:
:
:
:
::Hi
::
:: Those meters can be so sensitive just holding a lead gives a reading. Try taking a reading with a resistor across the leads.
::
::Norm
::
:::
:::I'm using a Wavtek 37XR Digital Voltmeter. I am measuring from Water Pipe Ground (Neg Lead) to the chassis (Positive Lead) in series.
:::
:::
:::
:::
:::
:::
:::
:::
::::Hi
::::
::::What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
::::
::::Norm
::::
::::
:::::Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
:::::-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
:::::
:::::
:::::
:::::
::::::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
::::::
::::::
:::::::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
:::::::
:::::::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
:::::::
:::::::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
:::::::
:::::::Good luck,
:::::::
:::::::Thomas
:Hi
:
: There will always be some leakage especially on humid days. Transformers are wound with wire separated by paper.
:
: Not a problem unless you get a spark and can draw current. Modern meters read voltage only drawing a micro amp or so..
:
:Norm
:
::Thanx Norm but they both (consoles) read 0 volts AC and 0 Volts DC when AC cord is plugged in one way. The only time I get these readings of AC and DC between ground and the chassis is when I reverse the AC plug and plug it in the other polarity/way. I think the Meter is fine. It's reading what is there and then what isn't there. So this leads back to the original question and that is, why do I read 120 AC and 60VAC between house ground (Water pipe) and the chassis on 2 different consoles when I flip the polarity of the AC cord? and 0 VAC or DC when I flip it back the other way.
::
::
::
::
::
::
::
:::Hi
:::
::: Those meters can be so sensitive just holding a lead gives a reading. Try taking a reading with a resistor across the leads.
:::
:::Norm
:::
::::
::::I'm using a Wavtek 37XR Digital Voltmeter. I am measuring from Water Pipe Ground (Neg Lead) to the chassis (Positive Lead) in series.
::::
::::
::::
::::
::::
::::
::::
::::
:::::Hi
:::::
:::::What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
:::::
:::::Norm
:::::
:::::
::::::Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
::::::-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
::::::
::::::
::::::
::::::
:::::::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
:::::::
:::::::
::::::::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
::::::::
::::::::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
::::::::
::::::::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
::::::::
::::::::Good luck,
::::::::
::::::::Thomas
Just guessing.. AC input winding is closest the core in most transformers. Seems reasonable the inside of the winding would have most leakage to the core. When the plug is one direction this part of the winding has AC, the other way it's zero.
Wouldn't expect to even see a spark. Do you read any resistance between chassis and AC input winding?
Norm
:Yes the current must be very low. As I just get a mild spark when putting the ground alligator clip on. That is what started the whole inquiry. I just wonder why the change of palarity makes the readings dissaper.
:
:
:
:
::Hi
::
:: There will always be some leakage especially on humid days. Transformers are wound with wire separated by paper.
::
:: Not a problem unless you get a spark and can draw current. Modern meters read voltage only drawing a micro amp or so..
::
::Norm
::
:::Thanx Norm but they both (consoles) read 0 volts AC and 0 Volts DC when AC cord is plugged in one way. The only time I get these readings of AC and DC between ground and the chassis is when I reverse the AC plug and plug it in the other polarity/way. I think the Meter is fine. It's reading what is there and then what isn't there. So this leads back to the original question and that is, why do I read 120 AC and 60VAC between house ground (Water pipe) and the chassis on 2 different consoles when I flip the polarity of the AC cord? and 0 VAC or DC when I flip it back the other way.
:::
:::
:::
:::
:::
:::
:::
::::Hi
::::
:::: Those meters can be so sensitive just holding a lead gives a reading. Try taking a reading with a resistor across the leads.
::::
::::Norm
::::
:::::
:::::I'm using a Wavtek 37XR Digital Voltmeter. I am measuring from Water Pipe Ground (Neg Lead) to the chassis (Positive Lead) in series.
:::::
:::::
:::::
:::::
:::::
:::::
:::::
:::::
::::::Hi
::::::
::::::What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
::::::
::::::Norm
::::::
::::::
:::::::Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
:::::::-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
:::::::
:::::::
:::::::
:::::::
::::::::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
::::::::
::::::::
:::::::::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
:::::::::
:::::::::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
:::::::::
:::::::::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
:::::::::
:::::::::Good luck,
:::::::::
:::::::::Thomas
:Hi
:
: Just guessing.. AC input winding is closest the core in most transformers. Seems reasonable the inside of the winding would have most leakage to the core. When the plug is one direction this part of the winding has AC, the other way it's zero.
:
: Wouldn't expect to even see a spark. Do you read any resistance between chassis and AC input winding?
:
:Norm
:
::Yes the current must be very low. As I just get a mild spark when putting the ground alligator clip on. That is what started the whole inquiry. I just wonder why the change of palarity makes the readings dissaper.
::
::
::
::
:::Hi
:::
::: There will always be some leakage especially on humid days. Transformers are wound with wire separated by paper.
:::
::: Not a problem unless you get a spark and can draw current. Modern meters read voltage only drawing a micro amp or so..
:::
:::Norm
:::
::::Thanx Norm but they both (consoles) read 0 volts AC and 0 Volts DC when AC cord is plugged in one way. The only time I get these readings of AC and DC between ground and the chassis is when I reverse the AC plug and plug it in the other polarity/way. I think the Meter is fine. It's reading what is there and then what isn't there. So this leads back to the original question and that is, why do I read 120 AC and 60VAC between house ground (Water pipe) and the chassis on 2 different consoles when I flip the polarity of the AC cord? and 0 VAC or DC when I flip it back the other way.
::::
::::
::::
::::
::::
::::
::::
:::::Hi
:::::
::::: Those meters can be so sensitive just holding a lead gives a reading. Try taking a reading with a resistor across the leads.
:::::
:::::Norm
:::::
::::::
::::::I'm using a Wavtek 37XR Digital Voltmeter. I am measuring from Water Pipe Ground (Neg Lead) to the chassis (Positive Lead) in series.
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
:::::::Hi
:::::::
:::::::What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
:::::::
:::::::Norm
:::::::
:::::::
::::::::Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
::::::::-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
::::::::
::::::::
::::::::
::::::::
:::::::::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
:::::::::
:::::::::
::::::::::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
::::::::::
::::::::::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
::::::::::
::::::::::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
::::::::::
::::::::::Good luck,
::::::::::
::::::::::Thomas
:6Megs from Chassis to each prong when it's turned on.(not pluged in of course. When off only 6M to one prong other is infinite.
:
:
:
:
:
::Hi
::
:: Just guessing.. AC input winding is closest the core in most transformers. Seems reasonable the inside of the winding would have most leakage to the core. When the plug is one direction this part of the winding has AC, the other way it's zero.
::
:: Wouldn't expect to even see a spark. Do you read any resistance between chassis and AC input winding?
::
::Norm
::
:::Yes the current must be very low. As I just get a mild spark when putting the ground alligator clip on. That is what started the whole inquiry. I just wonder why the change of palarity makes the readings dissaper.
:::
:::
:::
:::
::::Hi
::::
:::: There will always be some leakage especially on humid days. Transformers are wound with wire separated by paper.
::::
:::: Not a problem unless you get a spark and can draw current. Modern meters read voltage only drawing a micro amp or so..
::::
::::Norm
::::
:::::Thanx Norm but they both (consoles) read 0 volts AC and 0 Volts DC when AC cord is plugged in one way. The only time I get these readings of AC and DC between ground and the chassis is when I reverse the AC plug and plug it in the other polarity/way. I think the Meter is fine. It's reading what is there and then what isn't there. So this leads back to the original question and that is, why do I read 120 AC and 60VAC between house ground (Water pipe) and the chassis on 2 different consoles when I flip the polarity of the AC cord? and 0 VAC or DC when I flip it back the other way.
:::::
:::::
:::::
:::::
:::::
:::::
:::::
::::::Hi
::::::
:::::: Those meters can be so sensitive just holding a lead gives a reading. Try taking a reading with a resistor across the leads.
::::::
::::::Norm
::::::
:::::::
:::::::I'm using a Wavtek 37XR Digital Voltmeter. I am measuring from Water Pipe Ground (Neg Lead) to the chassis (Positive Lead) in series.
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
::::::::Hi
::::::::
::::::::What are you using for a meter? Digital meters have little loading so read any slight leakage. Put a resistor across your meter leads and see what you read. Try 4.7 to 10K. With this loading voltage should about disappear.
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::::::::Norm
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:::::::::Are you sure about this shorted transformer thing Thomas? I measured my other console and Got 60VAC and
:::::::::-10VDC doing the same test. And when I swapped the plug Zero like the other one. Anyone else?
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::::::::::I just re-checked with the voltmeter on AC this time and 120 between house ground and chassis only when polarity of cord is one way, the other way is fine. I unplugged the rectifier to test so definatly not from the circuit. So does this mean the transformer is faulty? How could this happen? COuld the negative (cold side) of AC just be touching the chassis or is the transformer casing touching AC cold line in? This is how people die buy not putting on a polarised cord and safety ground isn't it?
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:::::::::::A note on your second message which I failed to read the first time: This would indicate that a leakage within the transformer of some type is very likely. I can mention a million scenarios, since a million or more are possible (all the different ways the transformer could be leaking), but the only thing that will tell the real tale is if you test the transformer. Seems like a transformer issue, though.
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:::::::::::Remember that DC cannot flow through a condenser, so if your radio had a condenser from the line to the chassis, this could not pass DC unless it was leaking (none is present, so omit that idea). DC also cannot flow through any capacitive coupling that takes place within the power transformer. That said, only a leak--a connection of some sort--will pass DC to the line cord.
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:::::::::::A regular wire to wire leak can develop, but if the transformer has been wet recently, this is also something to consider. If it was wet in the past, this could also have caused leaks by forming mineral trails.
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:::::::::::Good luck,
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:::::::::::Thomas
Thomas
Thomas